Pipette



Oct. 26, 1954 H. G. cREcl-:Lxus

PIPETTE Filed July 9, 1952 Patented Oct. 26, 1954 PIPETTE Harry G. Crecelius, Phoenix, Ariz., assigner to @Wens-Illinois Glass Company, a corporation of Ohio Application July 9, 1952, Serial No. 297,955

2 Claims. 1

This invention relates to pipettes and particularly to pipettes intended for use in bacteriology or serology.

In using pipettes in bacteriology or serology, it is customary to place a plug of cotton or other cellular material in the end of the pipette to prevent the passage of bacteria either from the mouth of the user to the liquid being handled, or from the liquid into the mouth of the user. rThis plug of cotton often becomes displaced in the pipette making its removal difficult, if not practically impossible. This occurs especially where one end of the pipette has a reduced diameter, as compared to the remainder of the pipette.

It is therefore an object of the invention to provide a pipette having a construction whereby this diculty is obviated.

Other objects of the invention will appear hereinafter.

The accompanying drawing shows a fragmentary part-sectional elevational View of a pipette embodying my invention.

As shown in the drawing, the pipette I is of substantially uniform internal diameter and uniform wall thickness throughout. The pipette is made of glass or other suitable material. The pipette has one end I I thereof tapered to form a dropper tip. The other end I2 is customarily referred to as the mouthpiece. As shown the pipette is formed with a constriction I3 near the mouthpiece thus separating the mouthpiece from the main body of the pipette.

The constriction I3 has a reduced internal diameter suiicient to prevent the displacement of a plug of cotton I5 or other cellular material downwardly into the pipette. The diameter of the constriction is not sucient however to materially affect the capillary action of the pipette.

The pipette may also be provided with calibration marks I4 or other indicia.

'I'he constriction I3 is preferably formed by heating the pipette in the localized region of the intended constriction and applying a suitable tool to the external surface thereof. As shown in the drawing, this causes a change in both the external and internal diameters.

By this construction, a plug of cotton I5 placed in the mouthpiece of the pipette is prevented from being displaced downwardly into the pipette.

Modications may be resorted to within the spirit and scope of the appended claims.

I claim:

l. A unitary pipette comprising a tube having one end thereof tapered to form a tip, said tube having a portion thereof between the tip and the other end and near and spaced from the other end restricted in such a manner that the interior diameter of the tube is reduced at said portion, the interior diameter above said portion toward the end of the tube being greater than the diameter of the restricted portion whereby a plug of cellular material inserted in the end of the tube is prevented from being displaced downwardly in the tube beyond the restricted portion.

2. A unitary pipette comprising a tube having one end thereof tapered to form a tip, said tube having a portion thereof near and spaced from the other end restricted in such a manner that the interior diameter of the tube is reduced at said portion, the interior diameter of said tube above said restricted portion being greater than the diameter at said restricted portion, and a plug of cellular material inserted in the end of the tube above said restricted portion, said restricted portion preventing the downward displacement of said plug of cellular material into the tube.

References Cited in the lle of this patent UNITED STATES PATENTS Number Name Date 1,791,829 McCrackan Feb. 10, 1931 2,348,831 Mathis May 16, 1944 2,376,231 conn May 15. 1945 

